Cleaner head for a vacuum cleaner

ABSTRACT

A cleaner head for a vacuum cleaner includes a body that defines a suction chamber, the suction chamber having a suction inlet for engaging a surface to be cleaned, and an outlet for fluid connection to a suction generator of a vacuum cleaner. The cleaner head further includes first and second brush bars each configured to contact a surface engaged by the suction inlet, and a drive mechanism which has an actuator. The drive mechanism is configured to rotate the brush bars about respective axes. The drive mechanism is also configured to rotate the first brush bar independently of the second brush bar, and to rotate the second brush bar independently of the first brush bar.

REFERENCE TO RELATED APPLICATIONS

This application claims the priority of United Kingdom Application No. 1606174.9, filed Apr. 8, 2016, the entire contents of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to the field of vacuum cleaners, and in particular to cleaner heads for vacuum cleaners.

BACKGROUND OF THE INVENTION

Cleaner heads may incorporate rotatable brush bars, such as those which are used to improve the cleaning performance of the cleaner head and thus of the vacuum cleaner as a whole. Such cleaner heads may be used with a vacuum cleaner that may be of any general type. For example, the cleaner head may be a fixed cleaner head on an upright vacuum cleaner, or alternatively it may be the cleaner head of a floor tool used with a cylinder vacuum cleaner or stick-vac cleaner.

It is conventional to provide the cleaner head of a vacuum cleaner with a rotatable brush bar. The design of the brush bar can be tailored to specific surfaces or circumstances. For instance, it is known to provide a cleaner head with a brush bar which has arrays of bristles for agitating or “beating” the fibres of a carpeted or upholstered surface to release dust therefrom. It is also known to provide a cleaner head with a brush bar that has pads of a soft pile material for wiping or polishing a hard surface such as a laminate or vinyl floor.

While tailoring the brush bar of a cleaner head to a particular surface may improve the pickup performance of the cleaner head when cleaning that particular surface, it can also result in a drop in performance when the cleaner head is used on a different surface. Existing attempts to address this problem generally result in cleaner heads that suffer from increased weight and bulk, increased complexity, reduced ease of use and/or reduced rotational power delivered to a particular brush bar.

SUMMARY OF THE INVENTION

It is one object of the present invention to mitigate or obviate at least one of the above disadvantages, and/or to provide an improved or alternative cleaner head or vacuum cleaner.

According to aspects the present invention, there is provided a cleaner head for a vacuum cleaner, the cleaner head comprising a body which defines a suction chamber, the suction chamber having a suction inlet for engaging a surface to be cleaned, and an outlet for fluid connection to a suction generator of a vacuum cleaner; first and second brush bars each configured to contact a surface engaged by the suction inlet; and a drive mechanism which has an actuator, the drive mechanism being configured to rotate the brush bars about respective axes, wherein the drive mechanism is configured to rotate the first brush bar independently of the second brush bar, and to rotate the second brush bar independently of the first brush bar.

The cleaner head according to aspects of the present invention having two brush bars may enable it to offer improved pickup performance, and/or satisfactory pickup performance on a wider range of surfaces than a cleaner head with a single brush bar. For instance, where the first and second brush bars are generally the same, this can provide an operator with the option to utilize both brush bars at the same time for a stronger sweeping or agitating action. As another example, a cleaner head according to the present invention can be provided with two different brush bars which are optimised for different kinds of surfaces, meaning that in comparison to a cleaner head with a single brush bar, for a given surface a cleaner head according to the present invention is more likely to have a brush bar which is suited to that surface.

In addition, aspects of the present invention enabling either brush bar to be rotated independently may provide further flexibility relative to a cleaner head with two brush bars that are not both rotatable independently. For instance, in a cleaner head according to the present invention the operator can be given the option to rotate only one of the brush bars, to rotate only the other one of the brush bars, or to rotate both brush bars simultaneously, depending on the particular surface to be cleaned and the nature of the dirt on that surface. This is discussed in more detail below.

Further, aspects of the present invention may allow the appropriate brush bar to be selected and rotated with advantageous speed and ease, in comparison to an arrangement with user-interchangeable brush bars. In comparison to an arrangement with an onboard brush bar selection mechanism, a cleaner head according to the present invention may have reduced weight and bulk, and/or reduced complexity (which may offer cost savings).

The drive mechanism being configured to rotate the first brush bar independently of the second brush bar should be understood to mean that the drive mechanism is able to rotate the first brush bar irrespective of whether or not it is rotating the second brush bar. Equally, the drive mechanism being configured to rotate the second brush bar independently of the first brush bar should be understood to mean that the drive mechanism is able to rotate the second brush bar irrespective of whether or not it is rotating the first brush bar.

The first and second brush bars may be arranged to contact a surface engaged by the suction inlet at the same time as one another.

This may allow an operator to utilise both brush bars at the same time (which may be beneficial when cleaning particular types of dirt or when cleaning particular types of surfaces). Further, it may allow an operator to switch between using (i.e. rotating) one brush bar to using the other brush bar without having to adjust the position of the cleaner head.

As an alternative, the first and second brush bars may be configured such that one of the brush bars contacts said surface when the suction inlet engages that surface in a first orientation, and so that the other of the brush bars contacts the surface when the suction inlet engages that surface in a second orientation.

The first and second brush bars may be spaced apart so that they do not touch one another.

This may allow more of the rotational power delivered to a particular brush bar to be utilised for improving pickup. In contrast, if the brush bars were positioned in contact with one another, some of the rotational power delivered to a brush bar would be used up overcoming friction between that brush bar and the other brush bar.

As an alternative, the first and second brush bars may be positioned in contact with one another, for instance so that one brush bar can act to remove dirt which had adhered to the other brush bar.

The drive mechanism may comprise a first actuator configured to rotate the first brush bar, and a second actuator configured to rotate the second brush bar.

This may provide an advantageously simple arrangement, when compared to an arrangement which utilises a single actuator. For instance, an arrangement with a single actuator needs to utilise two drive trains, and a mechanism for selectively engaging each drive train (for instance a pair of clutches).

In other embodiments, however, the drive mechanism may include a single actuator, each bar being selectively engageable with that actuator. This may be beneficial in terms of reducing the cost of manufacture of the cleaner head.

The or each actuator may be an electric motor.

As an alternative, the or each actuator may be a turbine arranged to scavenge energy from a dirty-air flow through the cleaner head (in essence, acting as an air motor). As another alternative, the or each actuator may be a surface-engaging wheel which is configured to be driven to rotate as a user moves the cleaner head over a surface to be cleaned, that wheel being drivingly connected to a brush bar.

In other embodiments, where the drive mechanism comprises two actuators the actuators may take different forms. For instance, one may be a turbine and the other an electric motor.

Optionally, the first brush bar has a first array of bristles; the second brush bar has a second array of bristles; and the bristles of the first array are less flexible than the bristles of the second array.

The two brush bars having bristles of differing levels of flexibility may tailor them to different types of surfaces, thereby increasing the breath of use of the vacuum cleaner. For instance, the first brush bar may be optimised for penetrating the fibres of carpet or upholstered surfaces, and the second brush bar can be optimised for sweeping and/or polishing surfaces such as laminate and vinyl floors (for instance the bristles can be in the form of soft pile).

The first array of bristles may take the form of one or more elongate strips. Each strip may be a continuous line of bristles, or an array of discrete bristle tufts.

The second array of bristles may extend over substantially all of an outer peripheral surface of the brush bar.

As an alternative, the first and second brush bars may be substantially identical. In such an arrangement independent control of the brush bars can be beneficial in that either one of the brush bars can be turned off, for instance if that brush bar has become tangled with hair, while still allowing cleaning to continue using the other brush bar.

One of the brush bars may comprise an array of carbon fibre bristles.

Where the first brush bar comprises the array of carbon fibre bristles, said array may be the first array, may be part of the first array, or may be provided on the first brush bar in addition to the first array. Similarly, where the second brush bar comprises the array of carbon fibre bristles, said array may be the second array, may be part of the second array, or may be provided on the second brush bar in addition to the second array.

The inclusion of carbon fibre bristles on a brush bar may be beneficial in that they can provide an anti-static action, for instance to assist in releasing fine dust that is clinging to a surface due to static electricity. Carbon fibre bristles can also provide a polishing action.

The carbon fibre bristles may be provided on the second brush bar.

The inclusion of the carbon fibre bristles on the second brush bar (where the second brush bar has more flexible bristles) can mean that they are provided on the brush bar which is tailored to surfaces on which carbon fibre bristles are of more use (e.g. hard surfaces such as laminate and hardwood flooring, which benefit more from polishing and on which fine dust adhesion is more of a problem).

Optionally, the cleaner head defines a front, a rear and an underside; the suction inlet is provided in the underside of the cleaner head; and one of the first and second brush bars is a front brush bar and the other of the first and second brush bars is a rear brush bar, the front brush bar being positioned generally in front of the rear brush bar.

The outlet may be provided at the rear of the cleaner head. As an alternative, the outlet may be provided at the top of the cleaner head.

In some embodiments, the front of a cleaner head may be considered to be the part of the cleaner head which faces in the same direction as an operator during normal use. Similarly, in those embodiments the rear of the cleaner head may be considered to be the part of the cleaner head which faces in the opposite direction to the user (i.e. faces towards the user). The underside of the cleaner head is the part of the cleaner head which faces downwards during normal use.

The rear brush bar may be the first brush bar and the front brush bar may be the second brush bar. Alternatively, the rear brush bar may be the second brush bar and the front brush bar may be the first brush bar.

The front brush bar may have an overall diameter which is less than the overall diameter of the rear brush bar.

For instance, the diameter of the front brush bar may be less than 80%, less than 70% or less than 60% of the diameter of the rear brush bar.

The front brush bar may be between 30 and 50 mm in overall diameter.

For instance, the front brush bar may be between 35 mm and 45 mm in overall diameter.

The drive mechanism may further be configured to allow the cleaner head to be used without either brush bar being rotated by the drive mechanism.

In other words, the drive mechanism may be configured such that during use either the first brush bar is rotated but not the second, the second brush bar is rotated but not the first, both brush bars are rotated, or neither brush bar is rotated.

Alternatively, the drive mechanism may be configured such that it in use at least one of the brush bars is rotated. In other words, it may be configured such that during use either the first brush bar is rotated but not the second, the second brush bar is rotated but not the first, or both brush bars are rotated.

According to a second aspect of the present invention there is provided a vacuum cleaner comprising a cleaner head according to the first aspect of the invention.

The vacuum cleaner may be an upright vacuum cleaner.

As an alternative, the vacuum cleaner may be a cylinder vacuum cleaner, a cordless or “stick-vac” vacuum cleaner, or a vacuum cleaner of any other suitable type.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which:

FIG. 1 is a perspective view of a vacuum cleaner which is useful for understanding the present invention;

FIG. 2 is a perspective view of a cleaner head of the vacuum cleaner of FIG. 1, viewed from below;

FIG. 3 is a perspective view of a cleaner head according to a first embodiment of the invention, viewed from above;

FIG. 4 is a perspective view of the cleaner head of FIG. 3, viewed from below;

FIG. 5 is a lateral cross-section through the cleaner head of FIGS. 3 and 4, at point A;

FIG. 6 is a perspective view of a cleaner head according to a second embodiment of the invention, viewed from above;

FIG. 7 is a lateral cross-section through the cleaner head of FIG. 6, at point B; and

FIGS. 8A and 8B are side views of a cleaner head according to a third embodiment of the invention, in different orientations.

DETAILED DESCRIPTION OF THE INVENTION

Throughout the description and drawings, corresponding reference numerals denote corresponding features.

FIG. 1 shows a vacuum cleaner 2 which is useful for understanding the invention. This example is an upright vacuum cleaner 2. It has a rolling head assembly 4 which carries a fixed cleaner head 6, and an ‘upright’ body 8. The upright body can be reclined relative to the head assembly 4, and includes a handle 10 for maneuvering the vacuum cleaner 2 across the floor. In use, a user grasps the handle 10 and reclines the upright body 8 until the handle 10 is disposed at a convenient height for the user. The user can then roll the vacuum cleaner 2 across the floor using the handle 10 in order to pass the cleaner head 6 over the floor and pick up dust and other debris therefrom. The dust and debris is drawn into a suction chamber (not visible) of the cleaner head by a suction generator in the form of a motor-driven fan (not visible) housed on board the vacuum cleaner 2. The dirt and debris enters the suction chamber through a suction inlet (not visible), and exits through a rear-facing outlet 11. From here, the dirt-laden air stream is ducted in conventional manner under the fan-generated suction pressure to a cyclonic separating apparatus 12 where dirt is separated from the air. The relatively clean air is then exhausted back to the atmosphere.

The cleaner head 6 is shown in isolation in FIG. 2, from underneath. From this perspective the suction chamber 14 and suction inlet 16 of the cleaner head 6 are visible. The suction chamber 14 is formed by a body 18 which in this case forms an outer casing of the cleaner head 6. The suction inlet 16 of this embodiment is provided in the underside of the cleaner head 6. In this case, the suction inlet 16 is delimited by front, rear and side walls 19 a, 19 b, 19 c, 19 d of the body 18. The lower edge of the front wall 19 a is higher than the lower edges of the rear and side walls 19 b, 19 c, 19 d. This allows dust and debris to pass under the front wall 19, rather than being “snowploughed” in front of it, when an operator pushes the cleaner head 6 forwards.

As also shown in FIG. 2, the cleaner head 6 has a brush bar 20 configured to contact a surface (generally a floor) which is engaged by the suction inlet 16. The brush bar 20 in this case is generally cylindrical, and is positioned generally transversely so that it projects radially out of the suction chamber 14 through the suction inlet 16. It has an array 22 of bristles which in this particular case take the form of three elongate rows of bristle tufts 24. In this case each row is generally helical in shape.

This particular brush bar 20 is tailored towards improving “pick up” on carpeted surfaces. The bristles of the array 22 are therefore relatively inflexible, so that they can penetrate carpet fibres. In use, the brush bar 20 is rotated about an axis (in this case its longitudinal axis 26) by a drive mechanism so that the bristle tufts 24 successively reach through the suction inlet 16 and penetrate the fibres of the carpet before returning into the suction chamber 14 through the suction inlet 16. This agitating action helps to dislodge stubborn dirt clinging to the carpet fibres so that this dirt can more easily be entrained in the airflow drawn into the cleaner head 6 through the suction inlet 16.

FIGS. 3 and 4 show a cleaner head according to a first embodiment of the present invention. The cleaner head 6 of this embodiment is suitable for use as part of a vacuum cleaner such as that shown in FIG. 1. Like the cleaner head of FIGS. 1 and 2, the cleaner head 6 of the first embodiment has a suction inlet 16, a body 18 which defines a suction chamber 14, and an outlet 11 for connection to a suction generator of a vacuum cleaner.

Whereas the cleaner head of FIGS. 1 and 2 had a single brush bar tailored to a single type of surface (a carpeted floor), the cleaner head 6 of this embodiment has two brush bars—a first brush bar 20 a and a second brush bar 20 b. In this particular case the two brush bars 20 a, 20 b are tailored towards different surfaces. The first brush bar 20 a is tailored towards carpeted floors, and the second brush bar 20 b is tailored towards hard surfaces such as hardwood, laminate or vinyl floors. The first brush bar 20 a of this particular embodiment has substantially the same structure as the brush bar of the cleaner head of FIGS. 1 and 2—it has a first array 22 a of bristles in the form of three elongate helical rows of bristle tufts 24. The second brush bar 20 b has a second array 22 b of bristles, but on this brush bar the array 22 b takes the form of a pair of mats 28 of soft pile which together extend over substantially the entire outer peripheral surface of the brush bar 22 b.

In this embodiment the first array 22 a of bristles is less flexible than the second array 22 b of bristles. Accordingly, the bristles of the first brush bar 20 a are better at penetrating carpet fibres, while the bristles of the second brush bar 20 b are tailored more towards providing a soft sweeping action on hard floors.

As well as the two mats 28 of bristles, the second brush bar 20 b also has an array 30 of carbon fibre bristles. In this embodiment the array 30 of carbon fibre bristles is provided separately to the second array 22 b. More particularly, the carbon fibre bristles are provided in two elongate axially-aligned rows of continuous bristles (only one of which is visible in FIGS. 3 and 4), each positioned between the two mats 28 which make up the second array 22 b.

The first and second brush bars 20 a, 20 b are spaced apart from one another so that in normal use they cannot touch and interfere with one another. In this case the second brush bar 20 b is positioned in front of the first brush bar 20 a. The second brush bar 20 b may therefore be referred to as the front brush bar, and the first brush bar 20 a as the rear brush bar.

Whereas the front of the suction inlet of the cleaner head of FIGS. 1 and 2 was delimited by a front wall, in this embodiment the front of the suction inlet 16 is delimited by the front brush bar 20 b. This allows the edge of the front wall 19 a of the body 18 to be higher than in the arrangement of FIGS. 1 and 2, thereby allowing larger debris to pass under it and enter the suction chamber 14. Ordinarily the edge of the front wall 19 a would be too high, and would provide an airflow path of sufficient cross sectional area that most air would enter the suction chamber 14 from the front, rather than from underneath, thereby reducing pickup performance. However, in this case the soft pile of the front brush bar 20 b provides a partial seal with the front wall 19 a, reducing the volume of air entering the suction chamber from the front to an acceptable level.

The front brush bar (i.e. the second brush bar 20 b in this case) is of smaller overall diameter than the rear brush bar (the first brush bar 20 a). More particularly, in this case the front brush bar 20 b has a diameter of around 50% of that of the rear brush bar 20 a (including their respective arrays 22 a, 22 b of bristles). This enables the front of the cleaner head 6 to reach closer into corners (such as corners between a wall and a floor). It will be appreciated, however, that if the front brush bar 20 b is to seal against the front wall 19 a so as to prevent excess airflow beneath the front wall 19 a, the maximum height of the edge of the front wall 19 a is limited by the diameter of the front brush bar 20 b. Further, the front brush bar should have a diameter large enough to provide bristles which are long enough to perform their function effectively. There is therefore a compromise to be struck in terms of front brush bar diameter. A diameter (including bristles) of between 30 and 50 mm, more particularly between 35 and 45 mm, is believed to represent the optimum for many circumstances. In the present embodiment the front brush bar 20 b has a diameter of around 40 mm.

The first and second brush bars 20 a, 20 b are each rotatable, independently of the other, by a drive mechanism. The drive mechanism is shown in FIG. 5. The drive mechanism 34 of this embodiment has two actuators, each in the form of an electric motor. A first electric motor 36 a is arranged to drive the first brush bar 20 a and a second electric motor 36 b is arranged to drive the second brush bar 20 b. Each electric motor 36 a, 36 b is connected to a pulley wheel 38 a, 38 b. The pulley wheels are arranged to drive corresponding pulley wheels 40 a, 40 b on their respective brush bars 20 a, 20 b via drive belts 42 a, 42 b. When the first electric motor 36 a is energised, it rotates pulley wheel 38 a, which rotates pulley wheel 40 a under action of drive belt 42 a, and the first brush bar 20 a rotates along with the pulley wheel 40 a. Similarly, when the second electric motor 36 b is energised, it rotates pulley wheel 38 b, which rotates pulley wheel 40 b under action of drive belt 42 b, and the second brush bar 20 b rotates along with the pulley wheel 40 b.

Since each brush bar 20 a, 20 b is drivable by its respective electric motor 36 a, 36 b, by controlling the two electric motors separately from one another (for instance using control electronics or a switching mechanism provided on the cleaner head 6 or elsewhere on the vacuum cleaner) the two brush bars 20 a, 20 b can be rotated independently of one another. In other words, the drive mechanism can rotate the first brush bar 20 a whether or not it is rotating the second brush bar 20 b, and can rotate the second brush bar 20 b whether or not it is rotating the first brush bar 20 a.

Independent rotation of the two brush bars 20 a, 20 b can allow the action of the cleaner head 6 to be more closely tailored to a particular set of circumstances. For example, in the present embodiment the cleaner head 6 can be tailored towards cleaning a hard floor by rotating the second brush bar 20 b so as to provide a sweeping action, but not rotating the first brush bar 20 a so as to avoid any potential marking of the surface by its stiffer bristles. Similarly, the cleaner head 6 can be tailored towards cleaning a carpet by rotating the first brush bar 20 a so as to provide an agitating action, but not rotating the second brush bar 20 b so as to avoid any risk of the second brush bar pushing dirt deeper into the carpet. Further, the cleaner head 6 can be tailored towards picking up particularly large debris by rotating both brush bars 20 a, 20 b, thereby ensuring that debris cannot clog behind or in front of a non-rotating brush bar.

The drive mechanism 34 of this embodiment is also configured to allow the cleaner head 6 to be operated with neither brush bar rotating. This may be useful, for instance to save power when the vacuum cleaner in question runs on batteries and the surface to be cleaned is only lightly soiled.

A second embodiment of the invention is shown in FIGS. 6 and 7. This embodiment is similar to the first embodiment, therefore only the differences will be described here. Whilst the drive mechanism of the first embodiment utilises actuators in the form of electric motors, in the second embodiment each actuator takes the form of a turbine 44 a, 44 b. The turbines 44 a, 44 b are positioned in respective passages 46 a, 46 b which are fluidly connected in parallel between the suction inlet 16 and outlet 11 of the cleaner head. In this particular embodiment the passages both run from the suction chamber 14 to the outlet 11. Some of the dirty air drawn into the outlet 11 through the suction inlet 16 passes through the passages 46 a, 46 b and drives the turbines 44 a, 44 b positioned therein. Rotation of the first and second turbines 44 a, 44 b is transmitted to the first and second brush bars 20 a, 20 b respectively, by pulley arrangements of the same general form as shown in FIG. 5.

In the second embodiment, independent rotation of the brush bars 20 a, 20 b by the drive mechanism is provided by valves 48 a, 48 b in the passages 46 a, 46 b. The first brush bar 20 a can be rotated by opening valve 48 a so that air can run through the passage 46 a and drive the turbine 44 a, and similarly the second brush bar 20 b can be rotated by opening valve 48 b so that air can run through the passage 46 b and drive the turbine 44 b.

In the first and second embodiments of the invention, the first and second brush bars 20 a, 20 b are positioned to contact a surface engaged by the suction inlet at the same time as one another. FIGS. 8A and 8B shows a third embodiment of the invention, and in this embodiment the brush bars 20 a, 20 b are configured to contact the surface 50 engaged by the suction inlet 16 when the cleaner head 6 is in different configurations.

In this embodiment, the suction inlet 16 is slightly convex (more specifically slightly chevron-shaped) so that it can engage the surface 50 over a range of angles of the cleaner head. When the cleaner head 6 is in a first orientation, in this case when it is at a relatively shallow angle to the surface 50 (shown in FIG. 8A), the first brush bar 20 a contacts the surface. When the cleaner head 6 is in a second orientation, in this case when it is at a steeper angle relative to the surface 50 (shown in FIG. 8B), the second brush bar 20 b contacts the surface 50 instead. The different angles of the cleaner head 6 is shown exaggerated in FIGS. 8A and 8B for the sake of clarity. In reality, the suction inlet 16 would generally be more gently convex so as to reduce air leakage under end of the suction inlet which is lifted from the surface 50.

It will be appreciated that numerous modifications to the above described embodiments may be made without departing from the scope of invention as defined in the appended claims. For instance, whilst in the second embodiment the rotation of the brush bars is controlled by opening or closing valves in the passageways of their respective turbines, in other embodiments they may be controlled by connecting or disconnecting parts of the mechanism leading from the turbines to the brush bars, for instance using clutches. As another alternative, the rotation of the brush bars may be controlled by selectively applying braking or locking mechanisms to the brush bars or their respective turbines.

Further, in other embodiments utilising turbines, the passages within which the turbines are provided may be configured differently. For instance, the passage of a turbine may be provided with an inlet on top of the cleaner head, rather than being supplied with some of the dirty air which enters the cleaner head through the suction inlet. As another example, the passage may both branch off from and return to the outlet of the cleaner head, rather than running between the suction chamber and the outlet. Further, in some embodiments a turbine may not be positioned within a passage, but may instead be positioned directly within the suction chamber of the cleaner head.

For the avoidance of doubt, where an embodiment comprises two turbines, the turbines and/or their respective passages (where present) may be configured differently to one another. Although the two turbines of the second embodiment are connected in parallel, in other embodiments they may instead be connected in series.

It is to be understood that a cleaner head according to the present invention may be incorporated within a vacuum cleaner of any suitable type, and that the features of the vacuum cleaner shown in FIG. 1 should not be construed as essential. For instance, the dust separator of a vacuum cleaner according to the invention may utilise a bag or a filter instead of or as well as a cyclonic separating apparatus.

Whilst the brush bars described above are provided with bristles, this should not be construed as essential. For instance, brush bars may instead be provided with a felt or woven fabric surface, or an array of elastomeric projections. Whilst in the above embodiments the brush bars are connected to their respective actuators by pulley arrangements, it is to be understood that in other embodiments a different mechanism may be used, such as a train of meshed gears.

For the avoidance of doubt, the optional and/or preferred features described above may be utilised in any suitable combinations, and in particular in the combinations set out in the appended claims. Features described in relation to one aspect of the invention, may also be applied to another aspect of the invention, where appropriate. Further, features described in relation to an apparatus outside the scope of the present invention may be applied to an embodiment of the invention. 

1. A cleaner head for a vacuum cleaner, the cleaner head comprising: a body that defines a suction chamber, the suction chamber having a suction inlet for engaging a surface to be cleaned, and an outlet for fluid connection to a suction generator of a vacuum cleaner; first and second brush bars each configured to contact a surface engaged by the suction inlet; and a drive mechanism that has an actuator, the drive mechanism being configured to rotate the brush bars about respective axes, wherein the drive mechanism is configured to rotate the first brush bar independently of the second brush bar, and to rotate the second brush bar independently of the first brush bar.
 2. The cleaner head of claim 1, wherein the first and second brush bars are arranged to contact a surface engaged by the suction inlet at the same time as one another.
 3. The cleaner head of claim 1, wherein the first and second brush bars are spaced apart so that they do not touch one another.
 4. The cleaner head of claim 1, wherein the drive mechanism comprises a first actuator configured to rotate the first brush bar, and a second actuator configured to rotate the second brush bar.
 5. The cleaner head of claim 4, wherein at least one of the first actuator and the second actuator is an electric motor.
 6. The cleaner head of claim 1, wherein: the first brush bar has a first array of bristles; the second brush bar has a second array of bristles; and the bristles of the first array are less flexible than the bristles of the second array.
 7. The cleaner head of claim 6, wherein at least one of the brush bars comprises an array of carbon fibre bristles.
 8. The cleaner head of claim 7, wherein the carbon fibre bristles are provided on the second brush bar.
 9. The cleaner head of claim 6, wherein: the cleaner head defines a front, a rear, and an underside; the suction inlet is provided in the underside of the cleaner head; and one of the first and second brush bars is a front brush bar and the other of the first and second brush bars is a rear brush bar, the front brush bar being positioned in front of the rear brush bar.
 10. The cleaner head of claim 9, wherein the front brush bar has an overall diameter that is less than an overall diameter of the rear brush bar.
 11. The cleaner head of claim 9, wherein the front brush bar is between 30 mm and 50 mm in overall diameter.
 12. The cleaner head of claim 1, wherein the drive mechanism is further configured to allow the cleaner head to be used without either brush bar being rotated by the drive mechanism.
 13. A vacuum cleaner comprising a cleaner head, the cleaner head comprising: a body that defines a suction chamber, the suction chamber having a suction inlet for engaging a surface to be cleaned, and an outlet for fluid connection to a suction generator of a vacuum cleaner; first and second brush bars each configured to contact a surface engaged by the suction inlet; and a drive mechanism that has an actuator, the drive mechanism being configured to rotate the brush bars about respective axes, wherein the drive mechanism is configured to rotate the first brush bar independently of the second brush bar, and to rotate the second brush bar independently of the first brush bar.
 14. The vacuum cleaner of claim 13, wherein the vacuum cleaner is an upright vacuum cleaner. 